Field of the Invention
The present invention relates to a differential device which is provided in a vehicle such as, for example, an automobile.
Description of the Related Art
Japanese Patent No. 4828847 has made known a conventional differential device in which a washer is interposed between a back surface of each of output gears and an input member (for example, a differential case).
In the above-mentioned conventional device, a meshing portion between the output gear and a differential gear are located further radially outward than a washer abutting surface, which abuts against the washer, in the back surface of each output gear. Accordingly, large thrust reaction force, which is transmitted from the differential gears via tooth portions in outer peripheries of the output gears, excessively concentrates on particularly outermost peripheral end portions of the washer abutting surfaces of the output gears. As a result, even though outer peripheral portions of the washers are extended further radially outward than the washer abutting surfaces so as to distribute load in washer receiving portions of the input member, load burden is locally large in the washer receiving portions. This is a disadvantage in reducing the thickness and weight of the input member. In addition, in order to bear the aforementioned large thrust reaction force, the tooth portions themselves in the outer peripheries of the output gears also need to be made sturdy by increasing in thickness in an axial direction.
Furthermore, such problems are disadvantageous for a differential device whose, particularly, input member and output gears are required to be reduced in thickness and weight, such as, for example, a differential device which is made thinner in an axial direction of the output gears of the differential device by making the diameter of the output gears sufficiently larger than that of the differential gears such that the output gears can have a sufficiently larger number of teeth than that of the differential gears.